RF communications systems are well known in the art. In many such systems, vehicles are equipped with mobile radios that allow an user to communicate with one or more base stations and also with other similarly equipped vehicles in the system. Such a system typically includes a vehicle mounted radio (hereinafter referred to as a mobile), an antenna and a handset (or microphone, speaker and control head). In addition, a base station at a remote system site generally communicates with the vehicle mounted equipment and typically serves to link the radio with a data terminal or operator.
The above configuration works well, so long as the user remains in the vehicle. Once the user moves beyond the operational range of the microphone, however, the user typically loses the ability to forward communications to the base station. To meet this problem, portable radios (hereinafter referred to as portables) have been used to allow the user to communicate with the base station when separated from the vehicle. The portable must, in order to be effective, emulate the mobile in all basic aspects, including frequency and signalling capabilities. Unfortunately, due to size and power supply constraints, known portables have failed to emulate some of the more important mobile characteristics including power output rating, speaker phone, diversity and speech recognition/synthesis capabilities.
In most every cellular system, each individual radio, portable or mobile, has one or more unique associated information sets, one of which includes NAM data (e.g., phone number, system ID, system channel scan data and serial number). The phone number of the NAM data is used by the cellular systems to identify the radio using the system.
In instances where the user controls both the portable and the mobiles, the user incurs an unjustified cost. Because each radio has its own unique telephone number, the user is billed separately for each radio. Thus, the user's minimum monthly costs are doubled.
There therefore exists a need to provide relatively inexpensive, effective, and reliable communications for those who ordinarily make use of a vehicle mounted radio but who must also carry on communications away from the vehicle from time to time.